This invention relates to a device integrated in a carding machine for processing textile fibers such as cotton fibers and the like. The machine cover facing the clothing of the main carding cylinder has an opening for the admission of air toward the cylinder clothing and further has at least one opening for the exit of air which entrains short fibers, trash and the like away from the cylinder clothing.
The main cylinder of the carding machine has a high circumferential velocity (in excess of 15 m/sec) and entrains a substantial amount of air on its surface. As a result, a vacuum is generated in the circumferential zone of the cylinder, that is, between the machine cover and the cylinder clothing. The fibers are, on the one hand, held by the teeth of the cylinder clothing and are advanced as the cylinder rotates and, on the other hand, are held back by the above-noted vacuum on the cylinder surface. By virtue of the cooperation between the carding cylinder and further carding elements, the fiber material is opened to obtain individual fibers.
In a conventional device as disclosed in European Patent No. 0 338 802 to which corresponds U.S. Pat. No. 5,075,930, there are provided, as viewed in the direction of rotation of the cylinder, first, second, third and fourth covers. The second cover is constituted by a clothed carding element situated radially closer to the cylinder clothing than the first cover. The third cover, as viewed in the circumferential direction of the cylinder, is separated from the second cover by a first gap and is disposed at a greater radial distance from the cylinder clothing than the second cover. The fourth cover, as viewed in the circumferential direction, is separated from the third cover by a second gap. The fourth cover has a separating edge which is shaped in such a manner that it deflects one part of the air stream from the cylinder clothing. Such air stream flows underneath the third cover during rotation of the carding cylinder. The narrow setting of the second cover forms an air barrier by means of which a pressure drop is generated immediately downstream of the second cover, that is, in the region of the first gap. Such a pressure drop is increased by the third cover which is situated at a greater distance from the cylinder surface than the second cover. As a result, the air current flows at an increased speed through the first gap. A screening device, positioned over the first gap, is so shaped that air in the first gap is drawn in only from the side of the carding machine. In such an arrangement the supply air is necessarily drawn in. The rotational air stream entrained by the cylinder is braked to a significant extent by the narrow setting of the second cover. The supply stream which enters only by suction is too weak to effectively detach short fibers, trash and the like from the long fibers and to remove such waste from the fiber mass. It is a further disadvantage that the air drawn in from the machine hall contains dust and the like which is introduced into the fiber material.
It is an object of the invention to provide an improved device of the above-outlined type from which the discussed disadvantages of the prior art are eliminated and which, in particular, in a simple manner ensures a better detachment and removal of short fibers, trash and the like from the fiber material and reliably prevents an introduction of dust and the like into the fiber material.
These objects and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the carding machine includes a main carding cylinder having a cylindrical surface carrying a cylinder clothing; a cover arrangement extending along a part of the cylindrical surface at a clearance therefrom to define a space between the cylinder clothing and the cover arrangement; a first opening provided in the cover arrangement and communicating with the space between the cylinder clothing and the cover arrangement; and a device for generating a pressurized air stream. The device communicates with the first opening for introducing the pressurized air stream through the first opening into the space between the cylinder clothing and the cover arrangement to impinge upon the cylinder clothing carrying fiber material thereon. A second opening which is provided in the cover arrangement communicates with the space between the cylinder clothing and the cover arrangement for removing the pressurized air stream, laden with waste material separated from the fiber material.
A separation and removal of short fibers, trash and the like from the fiber material carried by the carding cylinder may be performed in a simple manner with the measures according to the invention. The pressurized air stream impinges on the cylinder surface from which the stream rebounds and carries impurities away from the cylinder. The strength of the pressurized air stream may be adjusted so that the separation and removal may be optimized. It is a further advantage of the invention that the introduced pressurized air stream contains no interfering impurities.